Obtaining zinc and/or copper from complex ores or the like.



J. R. WILLIAMS & H., W. @L B. BRADLEY. OBTAINING, ZINC AND/0R COPPER PROM c UMPLBX ORBS 0R THB LIKE.

- APPLIOATION FILED 00.21.1909. 1,006,330.

Patented Oct. 17, 1911 2 .SHEETS-EHEIM' l.

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A LR. WILLIAMS 6; H. W. s B. BRADLEY. OBTAlNING ZINC AND/0R COPPER FROM COMPLEX OEES 0R THE LIKE. APPLIOATIOH HL2 AUG. 9, 1909,

1,006,330, Patented o@t.17,1911.

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Y, TED, sTArEs PATENT oBrion.;4

- JOHN-R.- WILLIAMS, "H'NRY W. BRADLEY, AND BENJAMIN BRADLEY, OF SHEEFIELD,

"1 oBTJarNING. zrNo AND/onscreen FROM COMPLEX cans on THE LIKE;`

To allwhom' it may concern.'

Be it known that We, JOHN RICHARD WIL LIAMS, HENRY WENrrwoRTH BRADLEY, and BENJAMIN BRADLEY, all subjects of the King kof Great Britain 'and Ireland, and residing at The Woods, Grenoside, Sheiiield, in the county of York, England, have invented certain new and useful' Improvements in Ob,- taining vZinc and/or Copper from Complex .Oresor the Like, of which the following is a specification..l y A y Our invention relates to obtaining zinc tiligd/or copper from complex ores and the 1 e. The yobject o'fthe present invention is to obtain the zinc and/or copper from ores and the like in which zinc or copper or zinc i of zinc and/or copper from silicate containing ores consisting in subjecting the same to the action of a very dilute solution lofsulfuric acid.

2 The invention also consists in separating the zinc and/or copper from the other materials in the ore to be treated by leaching with a slightly acid solution of zinc or copper sulfate preferably of low concentration but of such .strength that substantially the zinc or copper alone is dissolved out and maythen be recovered by electric deposition. 1 x .l

The inventionfurther consistsin a continnous process for-i the extraction of zinc and/or copper in which the Voreor the like is first leached with a slightly acid solution of zincor copper sulfate, the solution being then runzoff yand the metall deposited electrolyticallyrwhile'the solution after electrolysis is returnedv `tothe leaching vessels and used again in the process.

The invention also consists in the method of extracting Zinc'hereinafter described.

Bylineans of our invention the Zinc can be extracted from ores which have heretofore not been treated commercially such' for instance as ore containing'from 5 to 15 per I Specification of Letters Patent. Application filed August 9, 1909. Serial No. 511,973.

Patented Oct. 17, 1911.

cent. of zinc mixed with lead andother substances. 4 1 l By the use of a solution of zinc sulfate which is only slightly acid the formation of .a gelatinous mass is practically avoided;

the electrodeposition on the vother hand. By

using a slightly acid solution for the leaching of silicate containin ores one batch may be leached many times y the same solution regeneratedvin each case by electrolysis and a correspondingly .large proportion of the metal contents extracted before such a quantity of gelatinous silica accumulates as to kprevent percolation which would result from the first or a very early treatment were a Asubstantially acid solution used. Indeed with our process the same solution may be used for many batches of ore. Even in orcs not containing silicates the economical operation of the process favors a weakly acid solution and with' a high current density in order to maintain such concentration a rapid flow of electrolyte in the cell is required; the deposition of impurities resultingf; from a slow flow being thereby also avoided. As regards the factor of gelatiuization' a 2 per cent. acid concentration may safely be em ployed, but asregards the dissolution of the cathode the limit is as low as .5 per cent. concentration, and for this reason in the case where the solution Yfirst leaches out the zinc and is then subjected to electrolysis an acid of .3 per cent. concentration is a very y .of this type.

In4 carrying 4thev invention into effect according to one example we place the crushed ore which has been subjected to any necessary .preparatory treatment as for example roasting in the case of sulid ores in a leaching vessel of suitable type. A. solu- :tion of zinc sulfate formed by dissolving the sulfate of zinc and made acid by treatment in an electrolytic bath or by direct addition of acid, is poured intothe leaching vessel and after acting on the'ore for the desired time passes out through a pipe at the bottom of the vessel or `by decantation into the electrolytic cell. The zinc sulfate may be formed by treating the ore itself with acid.

An electrolytic cell particularly applica- Fig. l.

Y Further distance pieces Z are This form consists of a number lof elec trodes which are arranged vertically parallel in a large box, a, which forms the cell. The cathodes, Z), are formed with lugs, c at their endsadapted to rest on supporting pieces, e,

extending the whole width of the box and dividing oil' spaces at the two ends of the box, the liquid being admitted into one of these spaces and withdrawn from the other. At one end each cathode rests on a plate of lead d. situated above the surface of the liquid, the several plates being connected up to bus-bars f outside the cell. IThe cathodes may be .made of iron, preferably .tempered and galvanized, and-the anodes of leadv plates. The anodes g' are placed one-on each side of each cathode so that both surfaces of the cathode are operative. The anodes are mounted in pairs, beingl soldered or otherwise connected one on each side of the prongs h of'fork-shaped pieces jf whose outer ends are attached to bus-bars if: the prongs of the fork-shaped pieces serving as distance pieces to separate a pair of anodes. provided at the end of the anode farthest from the fork wooden rails grooved to receive the top edges of each. pair of anodes, and at the bottom by suitable covering pieces. The side edges of theI anodes fit into vertical rails 0 grooved to receive them and between the vertical rails at their upper ends are formed inclined -surfaces to guide. the

cathodes b Vinto their correct position, and

at the water level holes p are made for the circulation of the liquid. The electrolyte is int'roduced into the `space at either end of the box, and the liquid passes longitudinally along the electrodes and out into the .space at the other end of the cell and so `to the outlet.

The object of the doubleanode g g above described the two parts being separatedbyl a wooden rail, is tol obtain mechanical strength and avoid the alterations of 'dis' tance .between the cathode and anode which would becaused by the wasting away ofa thick electrode where mechanical strength is obtained by thickness of metal. It will be seen further that in the cell above described allthe parts contained inthe main box a forming the cell are loose and may be readily lifted out when it is desired to clean the cell, it being thus possible readily to .flush the cell or shovel out the deposit or otherwise remove it. lVhen the various parts are in position it will be seen that the cell really consists of a number of practically separate cells parallel to each other. lVhen the cell is in operation it is found that the deposit of zinc is uniform this being assisted by the4 small distance between the plates and the closed-in form of the spacesbetween the anodes and the considerable mechanical agitation caused by the escaping gas formed during electrolysis.

The solution used may contain 5 per cent. or more of neutral zinc sulfate of the composition ZnSOA. 71120. It is desirable to use a solution of about 6 per cent. to S per cent.

strength the amountof zinc precipitated from a solution of greater concentration per ampere hour substantially not increasing whereas the proportionate loss of zincsolu.- tion in the extracted ore is much greater. lVith solutions of lesser concentration the etliciency of the electrolysis is greatly impaired. F or example in a series of experiments in which the current was Vpassed at the same voltage through identical cells containing solution varying in strength of lfrom 1% of neutral zinc sulfate to 16% of zinc sulfate, an equal rate of deposition (about 17 vgrains per ampere hour) was observed from 16% down to 5% but below this concentration the rate of deposition was found to be materially decreased. These experiments repeated with the samesolutionscontaining an addition of 0.3% ofv sulfuric acid gave practically identical results. It is found that if the current density does not exceed 114 amperes per square foot of lead surface exposed the anodes may run continuously for 300 days without renewal. It is preferable, to work with a current density of about 10. amperes per square foot of surface. The electrolyte, we find, as it comes from the cell, possesses greater activity when used for extracting Zinc from ore than would be expected from rthe quantity of acid contained. 7e find it preferable to .begin the electrolytic process with a neutral solution.

Another form ofelectrolytic cell which is suitable for use in'ithe'. Vresentproce'ss is provided `with. an anode. ormed preferably of a'lead plate, although carbon may be used. The cathode .may alsol be in the form of a plate, ,and in such a case a channel is cutfin the'..,-Wa-ll of the cell` adapted to receive the edges of the plate, leaving however, a space full of electrolyte between the plate and the Wall of the channel. 'The- 'effect of protecting the edges of the plate in this Way is that growths 'are 'prevented on its edges 'when' high currentdensities are used; The anodelshonld at the-same timebeplaced at Such ,a'distance from the cathode that formation of irregular growths on the surface ofthe' late is avoided.

i PWe nd that -in a cell constructed as above described a considerable current density per square foot of surface can be used and a sufliciently uniformsmooth 'deposit still obtained.

When a sufficient quanti y of zinc has been deposited in the cell on galvanized iron cathodes, the said cathodes are removed and the zinc stripped or melted off them by dipping into a bath of molten zinc or it may beremoved in lany convenient manner, for if the cathodes are of zinc thelwhole may be melted down; p v In the above described process the slightly acid sulfate of .zinc solution dissolves out the `zinc f om the ore and then passes into the electr lytic cell 'Where zinc is deposited on the cathode and -sulfuric acid formed so that a slightly acid solution may continually be vpassed through the apparatus.

Y It lwill be obvious that other forms of electrolytic cell than ,that above described may be used for carrying out the process, 40 the essential features of the invention being the use of a slightly acid and a more or less dilutesolution' of zinc sulfate containing such a low percentage of acid that it acts principally on the zinc or zinc and copper loavinglead but little attacked and does not gelatinize the mass so that the acid used in the leachingv bath is restored in the electrolytic cell and can be employed again in a'v continuous process if so desired.

` Whereas this process has been described as applicable tothe extraction of Vzinc it may be equally applied in the extraction of Iores containing copper either as silicate or in other combinations in which case the zinc 65. `sulfate solution is replaced by coppersul fate the other general features remaining unaltered. Where zinc and copper occur together itl will be evident that these may be leached out "together and recovered separately by electrodeposition the separation being effected by a suitable arrangement of the electrical conditions in the vat.

-Having noW described our invention what we claim and desire to secure by Letters Fat 5'ent iss-4 1. A continuousA recess` forthe of zinc, copper orfoth fro'rnsores including"y leaching the same Vwith a solution of sulfate of one or both of these metals'of low'con centration containing a small'percentage of ,Y free sulfuric acid, electrolyzing thev hquor`lv to remove onl v,enoughmetal to regenerate the solution of low acidity and of substa-n-v I tially the 4,riginal composition and then eni- -ploying it for furtherleaching; as and'ffor the purposes set forth.

2; A process from ores, including leaching the same with a solutioniof zincsulfa-te containing about.. 8% ofthemetallic sulfate and about 0.3%.

of free sulfuric acid, electrodepositing a portion of the metal substantially equivalent to the amount extracted from the ore the amount extracted and employing the solution for further leaching; as set forth.

4.- A process for the extraction of zinc, copper or both from ores consisting in leaching the same with a solution of the sulfate of one or both of these metals of loW concentration, containing a small proportion of free sulfuric acid and recovering a portion of the metal sufficient to regenerate this solution by passage of the liquor in a relatively thin film at high speed between an anode surface and a cathode surface in an electrolytic cell; as set forth.

5. A process for the extraction of zinc, copper or both including leaching the ore with a dilute solution of sulfuric acid until the acid is exhausted, reacidifying the solution to substantially its initial concentration and repeating the operation until a solution containing a substantial quantity of metallic sulfate is formed; electrolyzing the solution removing therefrom sufiicient metal to reproduce a solution of the initial acidity and employing'this for `further leaching; Vas set forth.

6. A process for the extraction of metals of the zinc and coppergroup from-silicate containing ores consisting in leaching the same with a solution of the sulfate of a metal of the group of lo7 concentration containing a small proportion of free sulfuric acid recovering the metal by passage of the solution in a relatively thin lfilm at highspeed between an anode surface and a cathode surface in an electrolytic cell ;l as set forth. f

7. A process for the extraction of 'metals forithe extraction of' zinc" of the zinc and copper group from silicate containing ores consisting in leaching the ore with a dilute solution of sulfuric acid until the latter is exhausted, withdrawing the solution reaoidifying the same to subv fate, electrolyzing the solution and removing by electrodepositionsuch a quantity of the metal as to reproduce a solution of substantially theinitial acidity and returning the same to the leaching vessels; as set forth.

In testimony whereof, We affix our signatures in presence of two witnesses.

JOHN R. wILLiAMs. H. W. BRADLEY. BEN. BRADLEY.

Witnesses: A ALBERT E. PARKER, l BERTRAM H. MAITHEWS. 

